c:\windows\system32\devmgmt.msc devmgr_show_nonpresent_devices=1
http://support2.microsoft.com/kb/315539
1. Click Start, point to All Programs, point to Accessories, and then click Command Prompt.
2. At a command prompt, type the following command , and then press ENTER:
set devmgr_show_nonpresent_devices=1
3. Type the following command a command prompt, and then press ENTER:
start devmgmt.msc